Question

The picture explains it all. I’ve painted a new Thumb and it goes off the JSlider area when at higher than 95 or below 5. I’ve tried padding the Track with no success.

Does anyone have any tips?

Here is my code. I believe my issue is fine turning the size of the thumb under the getThumbSize override.

private static class MySliderUI extends BasicSliderUI {

    private int thumbHeight = 22;
    private int thumbWidth = 22;

    public MySliderUI(JSlider b) {
        super(b);
        // this.thumbHeight = slider.getHeight();
        // this.thumbWidth = slider.getHeight();
    }

    @Override
    protected Dimension getThumbSize() {
        return new Dimension(thumbHeight, thumbWidth);
    }

    @Override
    public void paintTrack(Graphics g) {
        Graphics2D g2d = (Graphics2D) g;
        Rectangle r = trackRect;
        r.width = 40; // (int) (0.15 * r.getHeight());

        float[] dist = { 0.1f, 0.5f, 0.9f };
        Color[] colors = { new Color(34, 177, 76), new Color(255, 242, 0),
                new Color(237, 28, 36) };
        Point2D start = new Point2D.Float(r.x, r.y);
        Point2D end = new Point2D.Float(r.x, r.y + r.height);
        LinearGradientPaint p = new LinearGradientPaint(start, end, dist,
                colors);
        g2d.setPaint(p);
        g2d.fill(r);
    }

    @Override
    public void paintThumb(Graphics g) {

        Graphics2D g1 = (Graphics2D) g;

        // Make a triangle - Arrow on Meter
        int[] x = new int[3];
        int[] y = new int[3];
        int n; // count of points

        // Set Points for Arrow
        Integer arrowX = thumbRect.x;
        Integer arrowY = thumbRect.y;
        x[0] = arrowX - 25;
        x[1] = arrowX - 25;
        x[2] = arrowX - 2;
        y[0] = arrowY - 17; // Top Left
        y[1] = arrowY + 27; // Bottom Left
        y[2] = arrowY + 5; // Tip of Arrow
        n = 3; // Number of points, 3 because its a triangle

        // Draw Arrow Border
        Polygon myTriShadow = new Polygon(x, y, n); // a triangle
        g1.setPaint(Color.black);
        g1.fill(myTriShadow);

        // Set Points for Arrow Board
        x[0] = x[0] + 2;
        x[1] = x[1] + 2;
        x[2] = x[2] - 3;
        y[0] = y[0] + 5;
        y[1] = y[1] - 5;
        y[2] = y[2];

        // Color colorMeter = robot.getPixelColor(x[2]+10, y[2]);

        // Draw Arrow
        Polygon myTri = new Polygon(x, y, n); // a triangle
        // Color colr = new Color();
        g1.setPaint(Color.yellow);
        g1.fill(myTri);

        // super.paintThumb(g); // replace with your fill()
    }

}

Answer 1

Override getThumbSize(), returning the dimensions of the bounding rectangle of your thumb. If not symmetric, you should account for the slider’s orientation.

Addendum: As an aside, the top of the thumb didn’t “fall off”; it was clipped. See Painting in AWT and Swing for more about the clip rectangle.